Gas turbine engines are known, and typically include a fan delivering air into a compressor, and also outwardly of the compressor as bypass air. The air is compressed in the compressor and delivered downstream into a combustion section where it is mixed with fuel and ignited. Products of this combustion pass downstream over turbine rotors, driving the turbine rotors to rotate. The turbine rotors in turn rotate the compressors and fan.
The fan and compressor are typically driven by the turbine rotors via shafts. Seals may be provided around the shafts.